.rp-calc-wrapper {
max-width: 800px;
margin: 20px auto;
padding: 30px;
background: #f9f9f9;
border: 1px solid #e0e0e0;
border-radius: 8px;
font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
color: #333;
}
.rp-calc-wrapper h2 {
text-align: center;
margin-bottom: 25px;
color: #2c3e50;
}
.rp-input-grid {
display: grid;
grid-template-columns: 1fr 1fr;
gap: 20px;
}
@media (max-width: 600px) {
.rp-input-grid {
grid-template-columns: 1fr;
}
}
.rp-field {
margin-bottom: 15px;
}
.rp-field label {
display: block;
margin-bottom: 5px;
font-weight: 600;
font-size: 0.9em;
}
.rp-field input {
width: 100%;
padding: 10px;
border: 1px solid #ccc;
border-radius: 4px;
font-size: 1em;
box-sizing: border-box; /* Ensures padding doesn't affect width */
}
.rp-btn-container {
text-align: center;
margin-top: 20px;
}
.rp-calc-btn {
background-color: #27ae60;
color: white;
border: none;
padding: 12px 30px;
font-size: 1.1em;
font-weight: bold;
border-radius: 5px;
cursor: pointer;
transition: background 0.3s;
}
.rp-calc-btn:hover {
background-color: #219150;
}
.rp-result-box {
margin-top: 30px;
background: #fff;
border: 1px solid #ddd;
border-radius: 6px;
padding: 20px;
display: none; /* Hidden by default */
}
.rp-result-header {
text-align: center;
font-size: 1.2em;
font-weight: bold;
margin-bottom: 20px;
border-bottom: 2px solid #f0f0f0;
padding-bottom: 10px;
}
.rp-metric-grid {
display: grid;
grid-template-columns: 1fr 1fr;
gap: 15px;
}
.rp-metric {
background: #fdfdfd;
padding: 10px;
border: 1px solid #eee;
border-radius: 4px;
text-align: center;
}
.rp-metric-label {
font-size: 0.85em;
color: #777;
margin-bottom: 5px;
}
.rp-metric-value {
font-size: 1.3em;
font-weight: bold;
color: #2c3e50;
}
.rp-positive {
color: #27ae60;
}
.rp-negative {
color: #c0392b;
}
.rp-content-article {
max-width: 800px;
margin: 40px auto;
line-height: 1.6;
color: #444;
}
.rp-content-article h2 {
color: #2c3e50;
margin-top: 30px;
}
.rp-content-article h3 {
color: #34495e;
margin-top: 20px;
}
.rp-content-article ul {
margin-bottom: 20px;
}
.rp-content-article li {
margin-bottom: 10px;
}
function calculateRentalROI() {
// 1. Get Values
var price = parseFloat(document.getElementById('rpPrice').value);
var downPercent = parseFloat(document.getElementById('rpDownPercent').value);
var interestRate = parseFloat(document.getElementById('rpInterest').value);
var loanTerm = parseFloat(document.getElementById('rpTerm').value);
var rent = parseFloat(document.getElementById('rpRent').value);
var vacancyRate = parseFloat(document.getElementById('rpVacancy').value);
var annualTax = parseFloat(document.getElementById('rpTax').value);
var annualInsurance = parseFloat(document.getElementById('rpInsurance').value);
var monthlyRepairs = parseFloat(document.getElementById('rpRepairs').value);
var upfrontCosts = parseFloat(document.getElementById('rpClosingCosts').value);
// Validate inputs
if (isNaN(price) || isNaN(rent) || isNaN(interestRate)) {
alert("Please enter valid numbers for Price, Rent, and Interest Rate.");
return;
}
// 2. Initial Calculations
var downPayment = price * (downPercent / 100);
var loanAmount = price – downPayment;
var totalCashInvested = downPayment + upfrontCosts;
// 3. Mortgage Payment (P&I)
var monthlyRate = (interestRate / 100) / 12;
var totalPayments = loanTerm * 12;
var monthlyMortgage = 0;
if (loanAmount > 0 && interestRate > 0) {
monthlyMortgage = loanAmount * (monthlyRate * Math.pow(1 + monthlyRate, totalPayments)) / (Math.pow(1 + monthlyRate, totalPayments) – 1);
} else if (loanAmount > 0 && interestRate === 0) {
monthlyMortgage = loanAmount / totalPayments;
}
// 4. Operating Expenses & Income
var monthlyTax = annualTax / 12;
var monthlyInsurance = annualInsurance / 12;
var vacancyLoss = rent * (vacancyRate / 100);
var effectiveGrossIncome = rent – vacancyLoss;
var totalMonthlyOperatingExpenses = monthlyTax + monthlyInsurance + monthlyRepairs;
// 5. Key Metrics
var monthlyNOI = effectiveGrossIncome – totalMonthlyOperatingExpenses;
var annualNOI = monthlyNOI * 12;
var monthlyCashFlow = monthlyNOI – monthlyMortgage;
var annualCashFlow = monthlyCashFlow * 12;
var capRate = (annualNOI / price) * 100;
var cashOnCash = 0;
if (totalCashInvested > 0) {
cashOnCash = (annualCashFlow / totalCashInvested) * 100;
}
// 6. Update Display
var resultBox = document.getElementById('rpResultBox');
resultBox.style.display = "block";
var cfEl = document.getElementById('resCashFlow');
cfEl.innerText = formatCurrency(monthlyCashFlow);
cfEl.className = "rp-metric-value " + (monthlyCashFlow >= 0 ? "rp-positive" : "rp-negative");
document.getElementById('resCoc').innerText = cashOnCash.toFixed(2) + "%";
document.getElementById('resCapRate').innerText = capRate.toFixed(2) + "%";
document.getElementById('resNOI').innerText = formatCurrency(annualNOI);
document.getElementById('resMortgage').innerText = formatCurrency(monthlyMortgage);
}
function formatCurrency(num) {
return "$" + num.toFixed(2).replace(/\d(?=(\d{3})+\.)/g, '$&,');
}
Understanding Your Rental Property Investment
Investing in real estate is a powerful way to build wealth, but simply buying a property doesn't guarantee a profit. Successful real estate investors rely on accurate data to determine if a deal is worth their time and money. This Rental Property ROI Calculator is designed to help you analyze the profitability of a potential investment by breaking down cash flow, Cash-on-Cash Return, and Cap Rate.
Key Metrics Explained
1. Monthly Cash Flow
Cash flow is the net amount of money moving in or out of your rental business after all expenses are paid. Positive cash flow means your property is generating income every month, while negative cash flow implies you are losing money to hold the property. The formula used is:
- Cash Flow = (Rent – Vacancy Loss) – (Mortgage + Taxes + Insurance + HOA/Repairs)
Consistent positive cash flow is essential for long-term sustainability and scaling your portfolio.
2. Cash-on-Cash ROI (Return on Investment)
This is perhaps the most important metric for rental investors. Unlike standard ROI which might look at the total loan value, Cash-on-Cash ROI measures the return on the actual cash you invested (Down Payment + Closing Costs + Rehab Costs). It tells you how hard your money is working for you.
- Formula: (Annual Cash Flow / Total Cash Invested) × 100
A Cash-on-Cash return of 8-12% is generally considered a solid benchmark for residential real estate, though this varies by market.
3. Cap Rate (Capitalization Rate)
The Cap Rate helps you compare the profitability of similar properties regardless of how they are financed. It assumes you bought the property entirely with cash.
- Formula: Net Operating Income (NOI) / Purchase Price
This metric is crucial when comparing two different properties to see which has better intrinsic value, separate from your mortgage terms.
Estimating Expenses Accurately
One of the biggest mistakes new investors make is underestimating expenses. When using this calculator, ensure you account for:
- Vacancy Rates: No property is occupied 100% of the time. A 5% to 8% vacancy allowance is standard.
- Maintenance & CapEx: Even if the house is new, you should set aside a percentage of rent (typically 5-10%) for future repairs like a new roof or HVAC system.
- Property Management: If you don't plan to be a landlord yourself, expect to pay 8-10% of monthly rent to a management company.
Conclusion
Use this calculator as a screening tool. If the numbers work here, it's worth doing a deeper dive into the property due diligence. Remember, the best investors walk away from far more deals than they accept. Let the math, not your emotions, guide your investment decisions.